<!DOCTYPE html>
<html>

<head>
    <meta charset="utf-8">
    <title></title>
    <script src="../js/vue.js"></script>
</head>

<body>
    <div id="root">
        姓: <input type="text" v-model="firstName"><br><br>
        名: <input type="text" v-model="lastName"><br><br>
        全名: <span>{{fullName()}}</span>
    </div>
</body>
<script>
    Vue.config.productionTip = false;
    new Vue({
        el: "#root",
        data: {
            firstName: "张",
            lastName: "三"
        },
        methods: {
            fullName(){
                return this.firstName+'-'+this.lastName;
            }
        }
    })
</script>

</html>